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L. A. MAXSQN COMPRESSOR CONTROLLING MECHANISM Filed Aug. 1, 1921 2 Sheets-Sheet 1 Dec. 30, 1 24- 1,521,034

L. A. MAXSON COMPRESSOR CONTROLLING MECHANISM Filed Aug. 1, 1921 2 Sheets-Sheet 2 Reservoir 52 zaiWa; 1

Press wre Patented Dec. 30, 1924.

UNITED STATES LOUIS A. MAXSON, OF CLAREMONI, i Mi CHINERY CUMPi-lrlil'ii, 1-K.

GOMPRESSOR-GQNTBQL Application. filed August 1,

in object of my invention is to grovlde an improved compressor controllin nem- U m nism. Another object of my invention is to provide an improved mechanism for conltro ling the operation of electrically driven compressors whereby the utmost economy in oporation may be realized. A further object of my invention is to provide an iniprm' comin-cssor controlling; mechanism adapt ed to unload the compressor and to sto. 1e same the erformance of one or both of these :lunctions being automatically regulated by the nature of the load on ll '2 compr :ssiin' system. Other injects o in iuveution will. apliear in the course of ll a following specification and the appended clai ln the ac-com mnying (ll'll'ifiiilll'fi 7 shown for purposes of illustration one bodiment which my invention may assume in practice.

in these drawings- Fig". l .is a view mainly in side elevation but partially in section oi a compressor s .'stem provided with (he illustrative "form of my improved mechanism.

Fin". 2 is a View in central loiuritudinal section llirougrh the illustrative emluidinuuit (it one element of my improved compressor ontrolling system.

F 3 is a diagrammatic view sho Wl no" ii 1.0

re. l on of the parts.

T' I .4. mg. 5 l5 a l mgmeinary in the c of electrically driven compressor systems. it is more economical to run the compressor s tem unloaded for a matter of several Lites, due to the low current consumption of GORP Um ATEIGN IIu. TO SULLIVAN MA- ..CHUSETTS.

.J an Serial 7:10. 489,093.

the motor when no more than a friction load being: carried, her than to stop the momd draw hear i upon the mains as is case in starting up the motor. Fur- Ll eriuorc wear upon t'ic Fniarting apparatus may he reducoc. by avoiding; the stopping of the motor except in instances when it will be Found advantageous from the standpoint economy to discontinue the compressor e. lit has been found possible in pracfor each compressor installation to as- -iiu the period of idle running which w'nld be equirulent in the terms of current and expense starting up the compressor driving motor and bringing the compressor up to speed.

lily invention consists of improved compressor controlling; mechanism adapted to be adjusted so that it may unload the compressor and not stop tie same it the rate of an consumption is such as to render the probable period of unloaded operation of the com r ssor than the predetermined pe riod tor which it would be financially economical to shut down the driving motor and n'hicl y a novel control system serves to stop the motor shortly after the compressor has been unloaded il the air consumption is not sucl as to render it economical to maintain the compressor driving; motor in operation until iii'irther pumping is needed.

in the accompanying" drawings in which have shown for purposes of illustration one "form which my invei'ition may assume in practice, a compressor is indicated at 1. This compressor comprises a cylinder 2 in which a piston 3 reciprocable by usual nicchanisu'i driven from the crank shaft 4. Suitable inlet valve mechanisms 5 are pro- :Eiuid from the compressor cylinder is discharged to line Y irom weir-h it passes to receiver 8. The inlet valve mechanisms 55 comprise inlet valves l which are adapted to be opened by atmospheric pressure upon creation of a suction in the ends of the cylinder during the suction strokes of the piston and which are adapted to be seated by light springs 11. Arranged in line with these valves are ]')lStO11S 12 ot a well-known construction which reciprocable in cylinders 13 and adapted to be mo ved by re- .er pressure transmitted to them through hralhh pipes jll and main pipe 15 under the control ecei compressor drivirg motor i9. 21 s: pullev serving to in inta'in the belt in contact with the major ion of the peripheries or the drivingwncol 17 and motor driving; pulley. For the purpose of ellecting stoppage ot' the motor 19 ii the event that this he tound dcsirahle a1 to acconplish this stoppa e promptly it it is to )e accomplished at all, i have provided i-- proverl mechanism cooperating; with the pilot valve 16, one illus rative form oil which is shown herewith. itetcrring to Fig. 3, the

generator ,9- snpplies current through the mains 22 and 23; to the motor M and the room :22 is controlled by a main line switch 524-. To simplify the di ilosure none of the motor starting equipment is illustrated er;- ecpt the main line switch 2%. The main line switch Qlconinises contacts 25 and adapted to he electrically connected by a switch menih-er 52? which is mounted upon a rod LS. and the latter is a lapterl to he moved in opposite directions by electro-magnets 29 and 30 respectively. It will he 4 7 that one end of each ot' these eleetromagnets connected to the main 23 while the other end of the winding of the magnet 29 is co ed to an electric eo'nJact he other end of the windin 230 connected to the contact 1; For the purpose ot maintaining i the circuits through ill; are broken. I eniph s indicated the this weight i lini g locatc tween the open and closed porrr' is switch member 2'? and lower end 01 the weight lever heing pivoted to the switch niemher wherrhv as t switch opens and closes the weight passes 'oni one sid to the other of a vertical lllrG Fulcrum 33.

position at c L l. and

nets oted wei gh he contact is iusuiateol y mounted, in.

this illustrative form of my invention upon the face of a pressure gauge 35 which is of relatively large size. The contact '78 is a movable contact and is carriech in this illustrative form of my invention, at the outer end or" a piston rod 37 to which it is pivotallv connected and relative to which it is held in a predetermi ieil position by a light spring 38. The piston rod 37 is provided with a suitably packed piston 38 reciprocahle in a cylinder 39 which cylinder is secured to the il ace of the gauge 35 in such manner that the contact 78 n in one position occupy a position corresponding to the contact T0 but spaced therefrom by a disterce equal to eight pounds on the gauge r adin The piston 38 is normally forced i, ially to the bottom of the cylinder 39 hv a spring ell) an d is adapted to he moved uov'iucly the cylinder l0 h fluid under I l 'ii'essure, herein. oil, supplied through a pipe 4? i" a reservoir lQ which is adapted to he subjected to receiver pressure upon openilot valve 16, fluid heing con- (w the line 15 by means ot a T 43 The pipe 41 is provided with to and the lower end ot the cylrovid d with an initial receiv- 11hr eh; from which by port t? controlled hv an achustahle needle valve t8. the

Cor

v I; a pilot switch.

Let it be assumed that it has heen culated or found by experiment the compressor remains unloaded nore t m nutes the quantity of current iised g will he l-ss if the motor is stopped than would he the case if tl e n otor were to he kept running with but the ligh load of ill) the unloaded compressor. It will be evident that it the compressor load is substantially constant over a considerable period of time the drop over a short period ct time will probably bea a definite proportion to the drop over a greater period of time. For example, if the receiver pressure drops from 80 pounds to 78 pounds in one minute, it will probably drop to '70 pounds in about live minutes. Now, let it be assumed that the needle valve L8 is so adjusted as to cause the piston 38 to move upward under the action of oil from the receiver 42 at such rate as to bring the contact 78 out to the arc in which the contact 70 lies in just one minute, and, assuming that the compressor unloaded at 80 pounds, it will be evident that it' the air consumption is less than at such a rate as to cause the compressor to be reloaded at the end cit lire minutes or less, the needle 36 will still have its extremity in such position as to be contacted by the contact 78 when the latter has reached its highest position, but that if the rate of use of air from the receiver 8 is such so as to cause the compressor to be reloaded in, say, three minutes the pressure drop will have been so rapid as to cause the needle 36 to have moved beyond the path of contact 78 prior to the instant when the latter reaches the arc in which the contact 70 is located. It will thus be evident that ii the load is such as to render it economical to stop the coinprcssor, the circuit controlled by the contact 78 and the needle will be closed and the compressor stopped, but if the air consumption is so great as to cause the compressor to be reloaded say in 1, 2, 3, or 1: minutes instead of some period over ive minutes, the needle 36 will. have moved so rapidly toward the contact 70 that it will not he touched by contact 78 at all and so that the compressor will not be stopped.

Noting now Fig. 3, it will be clear that the compressor motor is idle, the switch 2stheing open and hence the needle 36 is moving in the direction of the arrow it any air is being used or leaking. lVhen this needle touches the contact 70 a circuit will be closed through the magnet 30 and the main line switch will be closed. The unloader valve 16 so adjusted as to cause the corn pressor unloading mechanism indicated by the parts 12, 13, etc, to reload the coiniressor at T pounds or slightly below. It will thus be evident that the motor will start first and the con'ipressor will then be loaded. Preferably, the pilot valve 16 will be so constructed that its reloading range is about 1 pound more than the range oi the electric control so that the motor will start the compressor before it is reloaded. When the pressure has been built up in the receiver ,8 to 80 pounds, the pilot: valve 16 will operate to unload the compressor and simultaneously will admit pressure to the reservoir 4:2. Under the action of this pressure, the oil will cause the piston 38 to be gin to rise in the cylinder 39. It the rate of use 'troni the receiver is such as to cause the compressor to turn over idly for, say, seven or eight minutes before reloading, the contact 78 will close the circuit with the needle 36 before the latter is moved under the influence of falling pressure out ot the path of travel of the contact 78 and thus the compressor will be shut down. On the other hand, it the rate of pressure drop is rapid due to the rapid use of air the needle 36 will move so rapidly that the circuit through the magnet 29 will not be closed at all and so reloading of the compressor will occur only when the valves are allowed to seat due to the action of the pilot valve 16. The fact that the needle 36 will contact with the member '70 will be immaterial since it will simply cause a. cur rent to pass through the magnet tending to close the switch which is already closed. its the windings of the magnets 29 and 30 are quite. line, there will be very little current used in this mechanism. and further it will be obvious that the current flow through these circuits will occur only during the time when the needle 36 is in contact with either ot the contacts, or 78 which condition exists only a relatively small portion of the time. If desired, antoniatic means could be provided to cause the switch 53 lon opening to break the cir cuit through the needle 36 and the contact: 78 and on closing to restore the circuit to condition to be closed while interrupting the circuit througl'i the magnet 30 which it has just closed, this being possible by arrang ing, for example, an auxiliary switch controlled by a movement of the weight 32 or by the movement of the rod 28 in each of the pilot circuits. One such arrangement is diagrannnatically shown in Fig. where the auxiliary movable switch members 79 and Rt) respectively cooperate with fixed contacts 81, 82 to interrupt the circuits through the solenoids 29, $30 after the solenoids have done their work. it being understood that the switches will be insulated in some suitable manner from the rod. It will be noted that the spring 38 exerts such a light pressure upon the contact 78 that the needle will not be bent or distorted as the contact 78 touches it.

Fron'i the t'iiiregoing description, it will be evident that my improved mechanism, so-to-spealz, ai'iticipates the load and regulates ti o compressor automatically in accordance with the prospective load. It will he understood that this device is primarily of use in installations where the rate of discharge of air or its use from the re ltll) ceiver is relatively constant. Such con ditions would be found in plants using a large number of small hand air motors for, on the average, approxin'iately the same number would be in use at all times or better put, the demand for air would not be rapidly fluctuating, but more or less uniform at any given time. Another type of installation in which this mechanism would be of utility would be in air lift pumping plants where the rate of discharge to a plurality of wells would be more or less constant depending upon the number of wells in use. The primary function of this device is evidently for use where the load is relatively constant or where the variations in load while not infrequent are sus tained over reasonably definite periods of time.

It is evident that a pressure gauge need not be employed, but that other mechanism especially designed for the purpose could be provided such as is shown in Fig. 6 where the cylinder 85 and piston 86 take the place of the cylinder 39 and piston 33 and where the mechanism 87 takes the place 0]": the pressure gauge 35. It is also evident that other means. for example a collapsible diaphragm, such as is shown at 88 in Fig. t, could be used instead of the cylinder 39 and piston 38. It will also be evident that an electrically controlled pilot valve could be substituted for the pilot l6 and be controlled by the needle 36 and additional fixed contacts. Such a mechanism would result in absolute synchronism of the needle moving mechanism and the mechanism for moving the contact 78 and so would be excellent in practice. In Fig. 4 such a mechanism is shown. It will here be evident that only the additional mechanism or the substitute mechanism is illustrated, the connections for controlling the motor starting and stopping switch 24: not being illustrated, as they would remain the same as in the diagrams of Fig. 3. Here it will be noted that a D-valve 90 controls the supply through a passage 91 to the oil reservoir and to the unloader through the passages 15' and 44 respectively, and that it also is adapted to connect these passages with a vent 93. For the purpose of moving the iii-valve 90, a pair of solenoids 94c and 95 are provided, the solenoid 95 being adapted to be energized when the needle 36 contacts with the contact Wit, the circuit then being between the wire 22, through the needle 36, contact 70#, solenoid 95, back to the wire 23, and as a result of this connection, the valve 90 will be shifted from the position shown in Fig. 4: to its opposite position and'will vent the lines 44 and 15 causing re-loading of the compressor. It will also be observed that in the position of the parts shown, the solenoid 9a is energized and so the valve 90 has been moved to the position occupied with the result that receiver pressure passes through the pipe 91 to the pipe 15 and to the pipe 44' to unload the compressor and to supply fluid to the tank 42.

It will be clear that the piston 38 and cylinder 39 could be replaced by an expansible diaphragm ot' a form now in common commercial use and with such a diaphragm, there would be no leakage whatever possible. It will be also evident that the pressure gauge is merely used for purposes ot illustration and that other mechanism tor accomplishing the same function could be devised.

Fi'hile I have in this application specifically described one embodiment which my invention may assume in practice, it will be understood that this form of the same is shown for purposes of illustration and that the invention may be modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. In a compressor system, in combina tion, a compressor, unloading means theretor, a driving motor for said compressor, means for starting and stopping said motor, and means governed by the rate of air consumption controlling the operation of said compressor system.

2. In a compressor system, in combination, a compressor, unloading means there tor, a driving motor "for said compressor, means for starting and stopping said motor, and means operative when said compressor is unloaded to control said last mentioned means to effect stopping of the motor it air consumption is at less than a. predetermined rate.

3. In a compressor system, in combination, a compressor, unloading means therefor, a driving motor for said compressor, means for stopping and starting said motor, means controlled by receiver pressure for controlling said first and second mentioned means, and means cont-rolled by the rate of air consumption affecting the control of said second mentioned means.

t. In a compressor system, in combina tion, a compressor, unloading means there" for, a driving motor for said compressor, means for starting and stopping said motor, and means operative when said compressor is unloaded to control said last mentioned means, said means being governed by the rate of air consumption.

5. In a compressor system, in combination, a compressor, unloading means therefor, a driving motor for said compressor, a control switch for said motor, means operative when discharge pressure exceeds a predetermined limit by a predetermined amount to unload said compressor and means operative to operate said control switch to stop said motor it said predetermined limit is exceeded tor a predetermined time.

6. In a compressor system, in combination, a compressor, unloading means therefor, including means operative to unload the same when a predetermined discharge pressure is reached, a driving motor for said compressor, and means for stopping said motor it the air consumption is at less than a predetermined rate.

7. In a compressor system, in combination, a compressor, a driving motor therefor, means for controlling said compressor system including means to unload the compressor and stop the motor, and means responsive to the rate of air consumption which determines whether one or both of said events shall occur.

8. In a compressor controlling system, in combination, a compressor, and a control mechanism comprising a member responsive to receiver pressure variations, a timing element, and means controlled by said member and element controlling the operation of said compressor.

9. In a compressor controlling system, in combination, a compressor, and a control mechanism comprising a member responsive to receiver pressure variations, an adjustable timing element, and means controlled by said member and element controlling the operation of said compressor.

10. In a compressor system, in combination, a receiver, a compressor, a driving motor therefor, unloading means i or said compressor controlled by receiver pressure, a motor control switch, and means operative to stop said motor shortly after said com pressor has been unloaded including a timing element, a cooperating receiver pressure. variation indicating element, and means controlled by the cooperation of said ele ments controlling said motor switch.

11. In a compressor controlling mechanism, in combination, a compressor, a mem her movable in accordance. with compressor discharge pressure variations, a member moving at a predetern'iined rate, said members moving in intersecting paths, and means controlled by the engagement of said members to effect control of said compressor,

12. In a compressor system, in combination, a driving motor, a compressor, a compressor discharge pressure controlled unloading means therefor, and means controlling the driving motor including mechanism controlled by said first mentioned means and governed by the rate of change in compressor discharge pressure.

13. In a compressor system, in combination, a compressor,unloading means therefor, a. driving motor, a switch therefor, and controlling means for said switch including a member operative in one position to etl ect closure of said switch, movement oi said member being controlled by compressor discharge pressure, and means adapted to cooperate with said member in another position thereof to eii'ect opening of said switch, said last mentioned means being movable in accordance with compressor discharge pressure and the cooperation of said member and means being controlled by the rate of compressor discharge pressure variations.

14:. In a compressor system, in combination, a compressor unloading means therefor, a driving motor for said compressor, a control switch therefor, and controlling means operative on the attainment of a predetermined compressor discharge pressure to cause said unloading means to unload the compressor and to thereafter cause opening of said switch or not in accordance with the demand for air.

15. In a compressor system, in combination, a compressor, unloading means therefor, a driving motor for said compressor, means tor starting and stopping said motor, and means operative when the compressor discharge pressure is in excess of a predetermined amount and governed by the rate of air consumption for controlling said last nentioned means.

it In a compressor system, in combination, a compressor, a member movable in ac cordance with compressor discharge pressure variations, a member moving to a predetermined position in a predetermined time, said members moving in intersecting paths, and means controlled by the engagement of said members to effect control of said compressor.

In testimony whereof I afiix my signature.

LOUIS A. MAXSON. 

